The present invention relates to a driving mechanism for movable handrails of escalators and other movable paths.
In general, the handrails of escalators and other movable paths are driven by means of frictional force. Therefore, it is necessary to keep a strong frictional engagement between driving rollers and the movable handrails. For instance, such a driving mechanism is known which has a spring means for biasing the movable handrails into a stronger engagement with the driving rollers. This driving mechanism is however inconvenient in that indentations tend to be formed in the surface of the handrails, during the suspension of the moving path, by means of driving rollers and guide rollers between which the handrails are clamped.
Various driving mechanisms have been proposed which are intended for overcome the above described drawback. For instance, Japanese Publication of Utility Model Application No. 50-30796 discloses a driving mechanism constructed to avoid the above stated drawback. This mechanism has a plurality of driving rollers and a plurality of guide rollers which are arranged at front and back sides of the handrails to clamp the latter. The driving rollers are disposed on sprockets coaxially for a simultaneous rotation therewith. These sprockets are adapted to be driven by a motor through a chain. These driving and guiding rollers are rotatably secured to respective frames which are connected mechanically in series by means of pins and grooves, so as to be moved along with the handrails. The pin-and-groove engagement allows the frames of the guiding rollers to move in a direction perpendicular to the handrails. The frame of the guiding roller is provided with a wheel and a V-shaped cam so that the frame may be lifted up as it performs a parallel movement. In operation, as the power of the motor is transmitted to the sprockets through the chain, the frames of the driving rollers and guiding rollers are moved in parallel with each other. Consequently, the frames of the guiding rollers are raised to lift the guide rollers and thereby press the handrails onto the driving rollers, so that a sufficiently strong frictional engagement is established between the handrails and the driving rollers to enable the latter to drive the handrails in a stable manner. However, even this driving mechanism suffers from the following drawbacks.
For the first point, this mechanism is too complicated. In addition, since the frames of the driving rollers are adapted to move in parallel, the chain is often loosened during, for example, suspension of the moving path. Due to this loosening, the chain is apt to get out of engagement with the sprockets when the moving path is restarted. Moreover, in this driving mechanism, considerably large forces are exerted between the pins and associated grooves, and between the wheels and the V-shaped cams, so as to cause a rapid wear at these parts and the mechanism becomes unable to work after a long time of use.
Other relevant prior art is as follows:
(1) Japanese Publication of Utility Model Application No. 51-28797(1976) entitled "DRIVING MECHANISM FOR HANDRAILS IN ESCALATORS AND THE LIKE" PA0 (2) Japanese Publication of Utility Model Application No. 51-49747(1976) entitled "DRIVING MECHANISM FOR HANDRAILS" PA0 (3) Japanese Publication of Utility Model Application No. 51-27592(1976) entitled "DRIVING MECHANISM FOR HANDRAILS". This discloses a driving mechanism in which guide rollers are pressed onto the driving roller by means of electromagnetic force.
These two publications are modifications of the above stated driving mechanism.